1. Technical Field
The present invention relates to compositions comprising analogues of purine nucleosides containing a ring-expanded (xe2x80x9cfatxe2x80x9d or xe2x80x9cRENxe2x80x9d, used interchangeably) heterocyclic ring, in place of purine, and an unmodified or modified sugar residue, pharmaceutically acceptable derivatives of such compositions, as well as methods of use thereof. In particular, these compositions can be utilized in the treatment of certain cancers, bacterial, fungal, parasitic, and viral infections, including, but not limited to, Acquired Immunodeficiency Syndrome (AIDS) and hepatitis.
The concept of the present invention can be extended to include pyrimidine nucleosides and pharmaceutically acceptable derivatives thereof.
2. Background Information
Acquired Immunodeficiency Syndrome (AIDS) has become the deadliest epidemic of the closing years of the 20th century (Benditt, J., Ed., xe2x80x9cAIDS, The Unanswered Questions,xe2x80x9d Science 260:1253-93 (1993); Mitsuya, et al., Science 249:1533-44 (1990); Fauci, Proc. Natl. Acad. Sci. USA 83:9278 (1986); Chemical and Engineering News Jan. 19, 1987, p. 30, Jan. 26, 1987, p. 18, Jun. 8, 1987, p. 6, Jun. 29, 1987, p. 25; Nov. 23, 1989, pp. 12-70; Jun. 26, 1989, pp. 7-16; and Jul. 5, 1993, pp.20-27). It is caused by a retrovirus called the human immunodeficiency virus (HIV). Retroviruses contain ribonucleic acid (RNA) in their genomes instead of deoxyribonucleic acid (DNA) as is the case with mammals, including humans, and many other bacteria and viruses.
When the virus infects host cells, it uses its own enzyme called reverse transcriptase to transcribe its RNA blue-print into a double-stranded DNA, using the host nucleotide pool. The newly synthesized viral DNA, known as provirus, then gets incorporated into host cellular DNA. The host genetic machinery is then utilized to crank out new viral particles which further infect other cells, and so on.
Several approaches are currently being undertaken to confront the virus, for example, immunological reconstitution, development of a vaccine, and antiretroviral therapy. This third approach is described herein.
While the most desirable approach to check the AIDS viral epidemic would be the development of a vaccine, there are compelling factors to suggest that this approach alone will not be adequate to halt the epidemic. These factors are: (a) unlike other retroviruses, by infecting T4-lymphocytes, the HIV eliminates the very component of the immune response that recognizes antigens, and (b) the virus undergoes continually rapid mutation, resulting in several variations of viral envelope proteins, and hence viral antigenicity. This is believed to be due to high error rates intrinsic to reverse transcriptase-catalyzed genome replication (i.e., 10 times as compared with that catalyzed by human DNA polymerases) (Presson, et al., Science 242: 1168 (1988); Roberts, et al., Science 242:1171 (1988)). Therefore, simply restoring an AIDS patient""s immune system, without eliminating or at least checking the extent of HIV infection, is unlikely to prove effective therapeutically. Thus, with the unlikelihood that the exponential growth and spread of the disease will be halted in the very near future by vaccine development, it is of the utmost importance to pursue antiretroviral therapy.
An antiretroviral therapeutic approach involves developing agents that can potentially suppress the replication of human immunodeficiency virus (HIV) by any of a number of mechanisms including, but not limited to, the following: (a) blocking the viral attachment to the target cell, (b) inhibiting the enzyme reverse transcriptase, and/or (c) blocking transcription and/or translation. While progress is being made on several fronts, the principal obstacle has been the non-specificity and/or toxicity of many otherwise promising antiviral agents. In this respect, exploitation of the intrinsically high error rate; Presson, et al., Science 242: 1168 (1988); Roberts, et al., Science 242:1171 (1988), of HIV reverse transcriptase to incorporate a chain-terminating nucleotide residue into the developing DNA (approach c) has good prospects for specificity.
As mentioned above, HIV reverse transcriptase makes 10 times as many errors as compared to other cellular polymerases (Presson, et al., Science 242: 1168 (1988); Roberts, et al., Science 242:1171 (1988)). Thus, the incorporation of the chain-terminating nucleotide residue has the potential advantage of specificity in that it is less likely that the normal cellular DNA polymerases would easily accept an aberrant nucleotide analogue. In fact, AZT (Mitsuya, et al., Proc. Natl. Acad. Sci. USA 82:7096 (1985)) (3xe2x80x2-azido-3xe2x80x2-deoxythymidine), DDI (2xe2x80x2, 3xe2x80x2-dideoxyinosine) (Mitsuya et al., Nature 353:269 (1991)) and DDC (2xe2x80x2,3xe2x80x2-dideoxycytidine) (Nasr et al., Antiviral Res. 14:125 (1990); Merigan et al., Am. J. Med. 88:11 (1990); Meng et al., Ann. Intern. Med. 116:13 (1992)), the currently approved therapy for AIDS, are known to operate by this chain termination mechanism. The other prospective drugs, for example, DDA and CS-87, are also known to be chain-terminators (Johnston et al., Science 260:1286-93 (1993); Mitsuya et al., Science 249:1533-44 (1990); Chemical and Engineering News Jan. 19, 1987, p. 30, Jan. 26, 1987, p. 18, Jun. 8, 1987, p. 6, Jun. 29, 1987, p. 25; Nov. 23, 1989, pp. 12-70, Jun. 26, 1989, pp. 7-16, and Jul. 5, 1993, pp. 20-27). Unfortunately, they all suffer from either unacceptable levels of toxicity or in vivo non-efficacy, e.g. AZT is toxic to bone marrow, DDC causes painful feet, and DDA and CS-87 are not adequately efficacious in vivo (Johnston et al., supra (1993); Mitsuya et al., supra (1990); Chemical and Engineering News Jan. 19, 1987, p. 30, Jan. 26, 1987, p. 18, Jun. 8. 1987, p. 6, Jun. 29, 1987, p. 25; Nov. 23, 1989, pp. 12-70; Jun. 26, 1989, pp. 7-16, and Jul. 5, 1993, pp. 20-27). Therefore, the search must continue for efficient chain-terminators with minimum toxicity so as to arrive at an ideal anti-AIDS drug.
Chain termination can occur by different mechanisms: AZT and the other drugs mentioned above, for example, lack the crucial 3xe2x80x2-OH function necessary for chain elongation. It is also possible that base-mispairing accompanied by considerable deviation of base-ribose conformation from the natural array leads to chain termination (see FIG. I) (Chidgeavadze, et al., FEBS LETT, 183:275 (1985); Chidgeavadze, et al., Biochim. Biophys. Acta, 868:145 (1986); Beabealashvilli et al., Biochim. Biophys. Acta, 868:136 (1986)).
Significant deviation of the 3xe2x80x2-OH group from the natural array would hinder incorporation of subsequent nucleotides into the growing polynucleotide chain and/or formation of the RNA-DNA hybrid, an important event occurring during reverse transcription. The potentially planar and aromatic nucleosides/nucleotides, which are described herein are thought to operate by this latter mechanism, as corroborated by molecular modeling studies. (Hxc3xcckel MO calculations on potential aromaticity of several heterocyclic aglycons were performed using the program xe2x80x9cHMOxe2x80x9d, available from Trinity Software, Campton, N.H.) Molecular modeling studies were performed on a Silicon Graphics(trademark) computer, employing CHARMm(trademark), interfaced with QUANTA(trademark), obtained from Molecular Simulations, Inc., Boston, Mass. However, several other possible mechanisms of action cannot be ruled out.
FIG. II(A) depicts a ten-nucleotide long oligomer containing all 10 natural nucleotides, FIG. II(B) shows the corresponding oligomer with 9 natural nucleotides plus a xe2x80x9cfatxe2x80x9d guanine (fG) nucleotide inserted at position 5 in place of G. FIG. II(C) is a space-filling model of FIG. II(B). Extensive ABNR (Adopted Basis Newton Raphson) energy minimization performed on each duplex, Molecular modeling studies were performed on a Silicon Graphics(trademark) computer, employing CHARMm(trademark), interfaced with QUANTA(trademark), obtained from Molecular Simulations, Inc., Boston, Mass., that was formed by hybridization of each oligomer with its respective complementary oligomer, shows that incorporation of a fG into a nucleic acid sequence results in considerable distortion of the double helix with severe disruption of base-pair hydrogen bonding leading to unwinding of the double helix starting from the deviant fG residue (see FIGS. II(B) and II(C)).
Implications are that the incorporation of an fG into the growing DNA chain during reverse transcription would (a) hinder incorporation of subsequent nucleotides, (b) cause base-pair disruption, mismatch, or frameshift, and/or (c) prevent formation of an RNA-DNA hybrid. Any or all of the above events lead to chain termination, and in turn, inhibit viral replication.
Even if an analogue is not a chain-terminator, the incorporation of such an aberrant nucleotide into DNA by HIV reverse transcriptase, could become self destructive, as the analogue may introduce multiple mutations in subsequent rounds of polymerization and accumulations of several such mutations would be lethal to the virus.
Still another possible mode of action that cannot be ignored is if any of the ring-expanded nucleosides turn out to be neither chain terminators nor to be incorporated into DNA. In that case, the inhibitory activity of the analogue may simply be due to its binding to one of the active or allosteric binding sites of HIV reverse transcriptase causing competitive, noncompetitive, or uncompetitive inhibition.
One other major pathogen causing severe consequences is the hepatitis B virus (HBV) which is largely prevalent in third-world countries. It is believed that 80% of the world""s liver cancer is caused by HBV. The U.S. currently has 1 million infectious carriers, and chronically active hepatitis will develop in over 25% of carriers and often progresses to cirrhosis. It is estimated that about 5000 people die from cirrhosis each year in the U.S. and about 1000 people die from liver cancer caused by HBV.
Hepatitis B virus (HBV) is a DNA (2xe2x80x2-deoxyribonucleic acid) virus that infects humans. It is a member of the family of viruses, collectively called hepadnaviruses. These closely related viruses selectively infect either mammalian or avian hosts. Mechanistic studies on the replication of these viruses have explored the important role of reverse transcription of an RNA intermediate, strongly suggesting the viability of reverse transcriptase as a logical therapeutic target.
Hepatitis B virus infections continue to be a major worldwide health problem (Centers for Disease Controls and Prevention. Morbid. Mort1. Weekly Rep., 1995:43-963, 1995). HBV infection is known to cause acute and chronic liver hepatitis which can lead to chronicity and liver cirrhosis. Worldwide there are some estimated 350 million chronic carriers of HBV and 1-2% of them die each year from infection related complications. Chronic carriage of HBV has also been strongly associated with hepatocellular carcinoma (Beasley, R. P., et al., Overview on the epidemiology of hepatocellular carcinoma, p. 532-535, In F. B. Hollinger, S. M. Lemon, and M. Margolis (ed.), Viral Hepatitis and Liver Disease, 1991).
Several nucleoside analogs have been shown to inhibit the replication of HBV in cell cultures and in animal models (Colacino, J. M., et al., Prog. Drug Res., 50:260-322, 1998; Chu, C. K., et al., Antimicrob. Agents Chemother., 39:979-981, 1995; Doong, S.-L., et al., Proc. Natl. Acad. Sci. USA., 88:8495-8499, 1991; Genovesi, E. V., et al., Antimicrob. Agents Chemother., 42:3209-3217, 1998; Innaimo, S. F., et al., Antimicrob. Agents Chemother., 41:1444-1448, 1997; Korba, B. E., et al., Antimicrob. Agents Chemother., 40:1282-1284, 1996; Lin, T.-S., et al., J. Med. Chem., 37:798-803, 1994; Lin, T.-S., et al., Biochem. Pharmacol., 47:171-174, 1994; Nicoll, A. J., et al., Agents Chemother., 42:3130-3135, 1998; Yokota, T., et al., Antimicrob. Agents Chemother., 35:394-397, 1991; Zhu, Y-L., et al., Antimicrob. Agents Chemother., 41:1755-1760, 1997). More recently, 2xe2x80x2,3xe2x80x2-dideoxy-L-3xe2x80x2-thiacytidine (3TC) has become the first and the only nucleoside analog that has been approved for the treatment of chronic HBV infection in humans. Several other pyrimidine and purine nucleoside analogs with either modified ribose or acyclic alkyl chains as the sugar moiety have been shown to exhibit anti-HBV activity (Colacino, J. M., et al., Prog. Drug Res., 50:260-322, 1998; Lin, T.-S., et al., J. Med. Chem., 37:798-803, 1994; Lin, T.-S., et al., Biochem. Pharmacol., 47:171-174, 1994). Some of these nucleosides are currently being evaluated for their ability to treat HBV infections in humans (Bowden, S., Antivir. Chem. Chemother. 8(supple1):77-82, 1997). For the majority of these nucleosides with anti-HBV activity, the sugar moiety of the molecule is modified to make them inhibitors of the viral polymerases. Some of the modifications which may impart antiviral activity to nucleoside analogs are: removal of 2xe2x80x2 and/or 3xe2x80x2-hydroxyl as in 3TC (Doong, S.-L., et al., Proc. Natl. Acad. Sci. USA., 88:8495-8499, 1991); substitution of cyclic ribose with an acyclic side chain as in acyclic phosphonate analogs (Nicoll, A. J., et al., Agents Chemother., 42:3130-3135, 1998); or removal of ring oxygen as in carbocyclic analogs (Genovesi, E. V., et al., Antimicrob. Agents Chemother., 42:3209-3217, 1998; Innaimo, S. F., et al., Antimicrob. Agents Chemother., 41:1444-1448, 1997).
Enzymes play a crucial role in regulating the purine and pyrimidine metabolism of normal as well as rapidly proliferating cells. This fact has led to considerable research in identifying, isolating, characterizing, and studying the specific physiological role of many enzymes. This, in turn, has led to the rational design of inhibitors of a variety of enzymes. The replication of DNA of a cancer cell or a pathogen is dependent upon the availability of the deoxyribonucleoside triphosphates: dTTP, dCTP, DATP, and dGTP. Nucleotides are synthesized as ribo- and/or deoxyribonucleotides either via the de novo pyrimidine and purine pathways or via the salvage pathway using the preformed exogenous nucleobases or nucleosides. These nucleotides are used for the synthesis of new DNA strands. When there are preformed exogenous nucleobases or nucleosides, the de novo pathways are inhibited and nucleotides are synthesized via the more economical salvage pathway. Division of a cancer cell can be significantly altered or stopped by interfering with either of these two pathways The rapidly proliferating cancer cells are in high demand for nucleotide pools. Inhibition of any of the enzyme-catalyzed biosynthetic pathways by a specific enzyme inhibitor would terminate or significantly reduce the production of purine and pyrimidine nucleotides and this will lead to the death of the cell. Compounds that selectively interfere with malignant cells including nucleoside analogues are of great importance (Sartorelli and David, Springer-Verlag: Berlin (1974); Hirsch and Kaplan Sci. Amer., 256, 76-85 (1987)).
Modifications of natural nucleosides have led to synthesis of therapeutically significant nucleoside analogues which are potent inhibitors of enzymes involved in nucleic acid biosynthesis and are important in the treatment of cancer and pathogenic diseases.
A few patents exist relating to 5:7-fused heterocycles and nucleosides. The compounds described therein have structural features similar to coformycin and pentostatin, the compounds depicted in FIG. 3.
In particular, U.S. Pat. No. 4,151,347 describes both coformycin and pentostatin.
U.S. Pat. No. 4,163,839 describes a coformycin analogue referred to as isocoformycin.
U.S. Pat. No. 4,713,372 describes a pentostatin analogue referred to as 2xe2x80x2-chloropentosatin.
U.S. Pat. No. 4,935,505 relates to coformycin analogues such as, for example, azolo diazepine.
The compounds described in the above-referenced U.S. patents are quite distant from those encompassed by the present invention.
The first aspect of the present invention relates to potentially planar and aromatic, ring-expanded analogues of purine, their nucleoside, nucleotide, and any other pharmaceutically acceptable derivatives thereof, bearing the general formula I, as shown below.
The second aspect of the present invention relates to non-planar non-aromatic ring-expanded analogues of purine heterocyclic bases, their nucleoside, nucleotide, and any other pharmaceutically acceptable derivatives thereof, bearing the general formulas II, III, and IV as shown below.
It should also be pointed out that because of their structural similarity to natural purines, ring-expanded nucleosides or nucleotides are an abundant source of substrates and/or inhibitors of enzymes of purine metabolism, as well as of those requiring ATP or GTP cofactors. Indeed, there is a precedence for their potential ability to inhibit enzymes of purine metabolism. The naturally occurring synergistic antitumor antibiotics, coformycin (Ohno et al., J. Am. Chem. Soc. 96:4326 (1974), Umezawa et al., Ger. Offen 2,453,649 (1975), Glazer, Rev. Drug. Metab. Drug. Interact. 105:3 (1980); Hawkins, et al., Nucleosides and Nucleotides 2:479 (1983)), and 2xe2x80x2-deoxycoformycin (pentostatin) (Woo et al., J. Heterocycl. Chem. 11:641 (1974), Baker et al., J. Am. Chem. Soc. 101:6127 (1079), Chan, et al., J. Org. Chem. 47:3457 (1982), Hanvey, et al., Biochemistry 23:904 (1984)), (see FIG. 3), are 5:7-fused nucleosides containing the imidazo [4,5-d][1,3] diazepine nucleus, and are the two strongest inhibitors of adenosine deaminase (ADA) known, with a Ki as high as 10xe2x88x9211. Another recently isolated natural product called azepinomycin, also a 5:7-fused system, but a non-nucleoside (see FIG. 3) containing the imidazo [4,5-e][1,4] diazepine ring, is reported to be an inhibitor of guanase (Umezawa, et al., Jpn. Kokai Tokyo Koho JP 58,159,494 [83,159,494]; Chem. Abstr. 100:137362x (1984); Isshiki, et al., J. Antibiot. 40:1461 (1987); Fujii, et al., Heterocycles 27:1163 (1988)). All three molecules and their synthetic analogues however, are non-planar or puckered (Acevedo, et al. Tetrahedron Lett. 24:4789 (1983), Acevedo et al., J. Heterocycl. Chem. 22:349 (1985), Acevedo, et al., J. Org. Chem. 51:1050 (1986)). They also possess tetrahedral geometry at the hydroxyl junction of their seven-membered ring, and therefore, are viewed as transition state analogue inhibitors of ADA (Agarwal et al. xe2x80x9cCoformycin and Deoxycoformycin: Tight-binding Inhibitors of Adenosine Deaminasexe2x80x9d, in xe2x80x9cChemistry and Biology of Nucleosides and Nucleotides,xe2x80x9d Harmon et al., Academic Press, New York, pp. 159-197 (1978)), or guanase (Umezawa, et al., Jpn. Kokai Tokyo Koho JP 58,159,494 83,159,494; Chem. Abstr. 100:137362x (1984); Isshiki, et al., J. Antibiot. 40:1461 (1987); Fujii, et al., Heterocycles 27:1163 (1988)).
The physiological significance of inhibiting ADA lies in the fact that the enzyme inactivates the otherwise potential antiviral and antitumor drugs such as 8-azaadenosine, ara-A or formycin by rapid hydrolysis to the corresponding inosine analogues. While the physiological significance of inhibiting guanase is less clear, several reports have recently appeared regarding detection of abnormally high levels of serum guanase activity in patients with liver disease like hepatitis (Shiota et al., Jpn. J. Med. 28:22 (1989), Ito et al., Hepatology 8:383 (1988)). High serum guanase activity has also been reported to be a biochemical indicator of rejection in liver transplant recipients (Crary et al., Transplant Proc. 21:2315 (1989)).
It should also be noted that, in addition to viruses, bacteria represent a medical therapeutic problem and experience has indicated that, over time, certain strains develop resistance to the commonly used antibacterial agents. It is now known that certain of the purine or pyrimidine nucleoside analogues are useful as antibacterial agents, particularly gram negative bacterial infections.
The compounds of the present invention can be used in the treatment or prophylaxis of bacterial infections. The compounds can also be utilized in the production of medications for the treatment or prophylaxis of bacterial infections. Particular bacteria against which the compounds of the invention are useful include Escherichia coli, Salmonella spp., Shigella flexneri, Citrobacter freundii, Klebsiella pneumoniae, Vibrio spp., Haemophilus influenzae, Yersinia enterolitica, Pasturella haemolytica, and Proteus spp. These agents are responsible for the following diseases: travelers"" diarrhea, urinary tract infections, typhoid fever, cholera, shigellosis, and veterinary diseases including enteritis, and colisepticaemia.
Furthermore, it is known that nucleoside analogues operate synergistically with a wide range of other therapeutic agents, enhancing the therapeutic effects of each in a non-additive manner, raising the therapeutic index, and reducing the risk of toxicities from either compound. The activity of the compounds of the present invention, against a wide range of viral and bacterial infections, as well as their novel mechanism of action, may therefore be particularly useful in combination therapies including various combinations of the present compounds with each other and with other therapeutic and/or synergistic compounds and pharmaceutically acceptable carriers. Such combinations have oral, topical, opthalmic, otic, nasal, intraperitoneal, subcutaneous, intervenous and suppository use. Furthermore, veterinary medical applications are also possible as well as use as a feed additive for vertebrate animals.
Typically, there is an optimum ratio of the compound(s) of the present invention with each other and/or with other therapeutic or potentiating agents (such as transport inhibitors, metabolic inhibitors, renal excretion or glucuronidation inhibitors such as probenecid, acetaminophen, aspirin, lorazepam, cimetidine, ranitidine, clofibrate, indomethacin, ketoprofen, naproxen, etc.) wherein the active agents are present in an optimum ratio. An xe2x80x9coptimum ratioxe2x80x9d is defined as the ratio of the compound(s) of the present invention with another therapeutic agent or agents such that the overall therapeutic effect is greater than the sum of the effects of the individual therapeutic agents. The optimum ratio is usually observed when the agents are present in ratios of 10:1 to 1:10, 20:1 to 1:20, 100:1 to 1:100, and 500:1 to 1:500. Occassionally, even a vanishingly small amount of one therapeutic agent will suffice to potentiate the activity of one or more other agents. In addition, the use of the compounds of the present invention in combinations is particularly useful in reducing the chance of the development of resistance.
In the antibacterial field, it has previously been found that a wide range of antibiotics is effective in potentiating the activity of nucleoside analogues. This includes agents such as benzylpyrimidines, pyrimidines, sulphonamides, rifampicin, tobramycin, fusidic acid, clindamycin, chloramphenicol, and erythromycin. Therefore, an additional embodiment of the present invention relates to a combination wherein the second agent is at least one of the above-mentioned antiviral or antibacterial agents or classes of agent. It should also be noted that the compounds and combinations of the invention can also be used in conjunction with immune modulating therapeutics and therapy.
In view of the above, the compounds of the present invention provide for a therapeutic combination of these compounds, or a pharmaceutically acceptable derivative thereof. At least one additional therapeutic agent may also be included. Furthermore, one compound of the present invention may also be combined with at least one known and commonly used therapeutic agent. Such grouping of compounds or agents will hereinafter be referred to as xe2x80x9ccombinations.xe2x80x9d The combinations may be administered together, for example, in a unitary pharmaceutical formulation, or separately, for example, as combinations of tablets, injections, or other medicaments administered at the same time or at different times with the goal of achieving the desired therapeutic effect.
A xe2x80x9cpharmaceutically acceptablexe2x80x9d derivative means any pharmaceutically acceptable salt, phosphonate, ester, or salt of such ester, or any other compound which is capable of providing the parent compound or compounds of the present invention or a therapeutically effective metabolite or residue thereof. Examples of pharmaceutically acceptable salts of the present invention and pharmaceutically acceptable derivatives thereof include phosphorus compounds and phosphonates, base salts, e.g., derived from an appropriate base such as an alkali metal, an alkaline earth metal, ammonium and mineral acid salts, such as the hydrochloride.
In view of the above, the present invention encompasses potentially planar, aromatic, ring-expanded (xe2x80x9cfatxe2x80x9d) heterocyclic bases, nucleosides and nucleotide compounds having the structure 
wherein:
R1, R3 and R5 are each independently selected from:
NH, NH2, O, OH, S, and SH;
NH-alkyl, N-alkyl, O-alkyl and S-alkyl wherein the alkyl group is C1-C20;
NH-aryl, O-aryl and S-aryl wherein the aryl group is a substituted or unsubstituted phenyl or heterocyclic group;
N-glycosyl and NH-glycosyl wherein the glycosyl group is selected from the group consisting of ribosyl, 2xe2x80x2-deoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-azidoribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-difluororibosyl, and mono-, di- and triphosphosphate derivatives thereof;
Nxe2x80x94(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2, NHxe2x80x94(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2, Oxe2x80x94(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2 and Sxe2x80x94(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2 wherein Rxe2x80x2 is selected from the group consisting of hydrogen, a C1-C20 alkyl group, H2PO3, H3P2O6, H4P3O9 and the alkali metal or alkaline earth metal salts thereof;
R2, R4, R6, R7, R8 are each independently selected from:
hydrogen, a C1-C20 alkyl group, an aryl group which is a substituted or unsubstituted phenyl or heterocyclic group, and an aralkyl group wherein the aryl and alkyl portions of the group have the definitions given above;
a glycosyl group wherein said glycosyl group is selected from the group consisting of ribosyl, 2xe2x80x2-deoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-fluororibosyl 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-azidoribosyl and mono-, di-, and triphosphate derivatives thereof;
(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2 wherein Rxe2x80x2 is selected from the group consisting of:
hydrogen, H2PO3, H3P2O6, H4P3O9, and alkali metal or alkaline earth metal salts thereof;
m is zero to 20, n is zero to 20, and a is zero or one; and
U, X, Y, Z, W, J, K, and L are selected from the group consisting of C, N, O, P, and S. U, X, Y, Z, W, J, K and L are selected from the group consisting of carbon (C) and nitrogen.
Formula I(B) can be 4,8-diamino-6-imino-1H-imidazo[4,5-e][1,3]diazepine wherein R, and R5 are NH2, R3 is NH, R7 and R8 are H, and a for R2, R4 and R6 is zero.
Formula I(B) can also be 4,8-diamino-1-benzyl-6-iminoimidazo[4,5-e][1,3]diazepine, wherein R1 and R5 are NH2, R3 is NH, R7 is H, R8 is benzyl (CH2Ph) and a for R2, R4 and R6 is zero.
Formula I(A) can be 6-imino-1H-imidazo[4,5-e][1,3]diazepine-4,8-dione, wherein R1 and R5 are O, R3 is NH; R2, R4, R6 and R7 are H, and a is zero for R8.
Furthermore, formula I(A) can also be 4,6,8-triimino-1-xcex2-D-ribofuranosylimidazo[4,5-e][1,3]diazepine, wherein R1, R3 and R5 are NH, R2, R4 and R7 are H, R6 is 1-xcex2-D-ribofuranosyl, and a for R8 is zero.
Furthermore, it must be noted that the present invention includes all chiral forms and stereoisomers of the compounds presented above.
As noted above, the present invention also includes compounds comprising non-planar, non-aromatic, ring-expanded (xe2x80x9cfatxe2x80x9d ) heterocyclic bases, nucleosides or nucleotides having the formula II 
wherein:
R1 and R2 are each independently selected from H, OR3, SR3, NHR3, CO2R3, CONHR3, CONHNHR3, CH2OR3, CH2NHR3, and CH2R3;
R3, R4 and R6 are each independently selected from:
hydrogen, a C1-C20 alkyl group, an aryl group which is a substituted or unsubstituted phenyl or heterocyclic group, and an aralkyl group wherein the aryl and alkyl portions of the group have the meanings given above;
R5 is selected from the group consisting of O, S and NH; and
R7, R8 and R9 each are independently selected from:
hydrogen, a C1-C20 alkyl group, an aryl group which is a substituted or unsubstituted phenyl or heterocyclic group, and an aralkyl group wherein the aryl and alkyl portions of the groups have the meanings given above;
a glycosyl group wherein said glycosyl group is selected from the group consisting of ribosyl, 2xe2x80x2-deoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-azidoribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2-fluororiboxyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2,3xe2x80x2-difluororiboxyl, and mono-, di- and triphosphate derivatives thereof; and
(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2 wherein Rxe2x80x2 is selected from the group consisting of:
H, H2, H2PO3, H3P2O6, H4P3O9, and alkali metal or alkaline earth metal salts thereof;
m is zero to 20, n is zero to 20, and a is zero or one; and
U, X, Y, Z, W, J, K, and L are selected from the group consisting of C, N, O, P, and S. U, X, Y, Z, W, J, K and L may be selected from C and N.
Formula II can be 4,5,6,7-tetrahydro-8-hydroxy-8H-1-xcex2-D-ribofuranosyl[4,5-d][1,3]diazepine-5-one wherein R1 is OH, R2, R4, R6 and R8 are H, R5 is O, R3 is H2, R9 is 1-B-D-ribofuranosyl, and a for R7 is zero.
Furthermore, it must be noted that the present invention includes all chiral forms and stereoisomers of the compounds presented above.
Additionally, the present invention includes non-planar, non-aromatic, ring-expanded (xe2x80x9cfatxe2x80x9d) heterocyclic bases, nucleosides or nucleotides having the following formulas III and IV: 
wherein:
R1 and R4 are each independently selected from O, S, and NH;
R3 and R4 are each independently selected from H, OR2, SR2, NHR2, CO2R2, CONHR2, CONHNHR2, CH2OR2, CH2NHR2, and CH2R2;
R2 and R6 are each independently selected from:
hydrogen, a C1-C20 alkyl group, an aryl group which is a substituted or unsubstituted phenyl or heterocyclic group, and an aralkyl group wherein the aryl and alkyl portions of the group have the meanings given above;
R7, R8, and R9 are each independently selected from:
hydrogen, a C1-C20 alkyl group, an aryl group which is a substituted or unsubstituted phenyl or heterocyclic group, and an aralkyl group wherein the aryl and alkyl portions of the groups have the meanings given above;
a glycosyl group wherein said glycosyl group is selected from the group consisting of ribosyl, 2xe2x80x2-deoxyribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-azidoribosyl, 2xe2x80x2,3xe2x80x2-dideoxy-2xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-fluororibosyl, 2xe2x80x2,3xe2x80x2-dideoxy-3xe2x80x2-difluororibosyl, and mono-, di-, and triphosphate derivatives thereof;
(CH2)mxe2x80x94XRxe2x80x2xe2x80x94(CH2)nxe2x80x94YRxe2x80x2 wherein Rxe2x80x2 is selected from:
hydrogen, H2PO3, H3P2O6, H4P3O9, and alkali metal or alkaline earth metal salts thereof;
m is zero to 20, n is zero to 20, and a is zero or one; and
U, X, Y, Z, W, J, K, and L are selected from the group consisting of C, N, O, P, and S.
Formula (IV) may be 4,5,7,8-tetrahydro-6-hydroxy-3H,6H-imidazo[4,5-e][1,4]diazepine-5,8-dione, wherein R1 and R5 are O, R3 is OH, R2, R4, R6, R7 and R8 are H, and a for R9 is zero.
Furthermore, it must be noted that the present invention includes all chiral forms and stereoisomers of the compounds presented above.
The present invention also includes a method of treating a viral, bacterial, fungal or parasitic infection in a patient or vertebrate animal comprising administering at least one of the compounds noted above in an amount sufficient to effect the treatment.
The virus causing the infection may be selected from the group consisting of human immunodeficiency virus, Human B lymphotropic virus, Herpes simplex virus, Varicella-zoster virus, Epstein-Barr virus, necrotic rhinitis, Malignant catarrh, Allerton virus, Equine herpesviruses, Neurolymphomatosis, Influenza viruses, Parainfluenza viruses, Adenoviruses, Rheovirus, Respiratory syncytial virus, Rhinoviruses, Coxsackie virus, Echo viruses, Epidemic gastroenteritis virus, Rubeola virus, Hepatitis viruses, cytomegalovirus and Papovavirus.
The compound can be administered subcutaneously, intravenously, intramuscularly, intraperitoneally, orally, topically, or by a combination thereof.
Treatment can involve administering at least one of the compounds of the present invention in combination with at least one other known therapeutic agent.
The present invention also includes a pharmaceutical composition comprising at least one of the above-compounds and a pharmaceutically acceptable carrier.
All U.S. patents and publications referred to herein are hereby incorporated by reference.